Process for converting petroleum oils



April 23, v1935.

/7 65H50( ENE W. M. CROSS PROCESS FOR CONVERTING PETROLEUM OILS Filed 4July 24, 1930 Wilrf/Z f7. 05055 j@ M7/am Patented pr. 23, 1935 NITED STATES PATENT OFFICE Walter M. Cross, Kansas Gasoline Products Company, inc., N. J., a corporation of lDelaware City, Mo., assignor to Newark,

Application July 24,1930, Serial No. 470,435

Claims.

This invention relates in general to the treatment of petroleum hydrocarbons and more particularly has reference to'a process of treating hydrocarbons in which the deposition of carbon 5 in the apparatus employed-is avoided.

' in carrying out the conversion is eliminated.

Another object of this invention is to provide a process of convertinghydrocarbons in which the products of conversion are mixed with a cooling medium prior to evaporating the same.

A further object of this invention is to provide a process of treating hydrocarbons in which hydrocarbons are subjected to conditions of conversion and in which the products of conversion are mixed with a cooling hydrocarbon having a relatively high latent heat of vaporization and then introduced into an evaporating stage.

A still further object of this invention is to provide a process of treating hydrocarbon oils wherein the. products of conversion are combined with a cooling medium in the nature of a hydrocarbon oil, which serves to retard the evolution of vapors in a subsequent vaporizing zone, and to produce a residual material which may be removed from the system and utilized as vfuel' oil.

With these and other objects in view which may be incident to my improvements, the invention consists in the several method steps and the parts and combinations to be hereinafter set' forth and claimed, with the understanding that the procedure of the several necessary elements may be varied without departing from the spirit and scope of the appended claims.

In order to make my invention more clearly understood, I `have shown, inrthe accompanying drawing, means for carrying the same into practical eect without limiting the improvements in their useful applications to the particular constructions which, for the purpose of explanation, have been made the subject of illustration.

In treating oil according to the process herein set forth, a charging stock may be placed under pressure by means of a pump l and forced into the heating elements of a furnace 2. As illustrated, the hydrocarbon oil undergoing treatment (ci, iessn is rst passed through a preheating element 3, arranged in the upper portion of the furnace, and

is then introduced into a lower heating element d, wherein the oil is heated to a relatively high temperature. The construction of the heating g elements 3 and 4 fis such that the hydrocarbon oil will, `of necessity, pass therethrough at a relatively high velocity. By causing the hydrocarbon oil to pass through the heating elements at a high velocity, deposition of carbon in the heating m elements will be avoided.

A relatively high pressure is maintained in the heating elements and the hydrocarbon passing therethrough is heated to a temperature sumcient to effect conversion of the oil. Due to the 15 rapid flow of the hydrocarbon oil through the heating elements, conversion of the oil is not effected, but the same is subjected to what may be termed incipient conversion.

Upon emerging from the heating elements i 2@ and It, the oil under conditions of incipient'conversion, is passed through a conduit 5 into a reaction chamber t. This chamber is preferably of a size sufficient to permita large body of the liquid hydrocarbon to` collect therein and to re- 25 main therein for a time sufficient to consummate the conversion instituted in the heating elements. Reaction chamber t may be heated and/or insulated against heat loss. I have shown a valve l in the conduit 5 by means of which a dier- 30 ential pressure may be established between the heating element i and the reaction chamber t. Under normal operating conditions, however, this valve remains open so that the same pressure is maintained upon both the heating and reaction 35 stages. The oil within the reaction chamber I5 is maintained under a pressure suiicient to prevent any substantial vaporization of the oil therein. Under the above conditions, it` will be found thatv substantially complete conversion of the hydrocarbon oil within the chamber 6 may be obtained.

Products of conversion may be withdrawn from the chamber 6 through the transfer line 8 controlled by valves 9 and III, and introduced into 45 an evaporator II maintained at a pressure sufciently low relative to that in the reaction chamber, vso that an evaporation of the products of conversion is eected. Vaporized material emerges from the upper portion of, the evaporator and passes through the transfer line I2, into the lower portion of a refluxing tower I3, which is of any construction suitable for dephlegmating vapors of the character passing through line I2. Eiiuent passing from'the upper portion of tower 55 I3 is conveyed through line lll to a gas separator i5, the liquid material being ltransferred to the gasoline tank i6, and the gases passing oif through the gas outlet il. Unvaporized material collects in the lower portion of the evaporator, and upon reaching a predetermined height, actuates a mechanism i3, which controls an outlet valve i9 in a discharge line 20. discharge line is adapted to convey unvaporized material from the lower portion of the evaporator through cooler or condenser 24, to the fuel oil tank 2l.

Refluxing tower i3 'is provided with an automatic outlet control mechanism I8' which controls an outlet valve i9 in a discharge line 2d. The reflux condensate may pass through conduit 22, controlled by valve 23, through the condenser 24 and into a storage tank 25, or may be passed through conduit 26 into a collecting tank 2l without being subjected to cooling in the chamber 24. The reux condensate may be passed directly from tank 21 by means of the line 28 to the charging pump I, to be forced through the cracking system.

-If the products of conversion pass directly from the reaction chamber to the evaporator, a large portion of the material will be vaporized, leaving a coke-like or asphalt-like bottom in the vaporizing chamber H, which is relatively useless as a commercialv product. In certain instances wherein an excessive amount of material has passed overhead, the bottom remaining in the vaporizing chamber contains an excessive amount of free carbon that may be diiicult to readily eliminate from the system.

By introducing an extraneous medium such as a refrigerant, which may or may not be a hydrocarbon oil, through the line 29, and combining it with the heated products of conversion, the vaporization in the chamber il may be retarded to the desired degree, permitting only those fractions to pass overhead which may be utilized as a recharging stock( when separated out in the dephlegmator, and such lighter products as may subsequently be collected as final distillate. As mentioned, this medium serves not only to retard vaporization and retain a larger quantity of the oil as a bottom in the vaporizing stage, but also serves to increase the fluidity of the bottom, giving a blended product which has properties rangingbetween those of the natural fuel oil and the bottoms recovered from the cracking operation. Among other properties, this blending will lower the cold test of the bottoms, which is normally too high when certain types of oils are employed as charging stocks.

The present invention contemplates the introduction as a refrigerant to retard the Vaporization of the products of conversion, any substance which may be found suitable for the purpose. For instance, .any of the well known refrigerants, preferably those which would not detrimentally react with the material undergoing treatment may be used. These refrigerants may or may not be miscible with the material undergoing treatment. 4

In certain instances, it may be found advantageous to liquefy the uncondensible gases resulting from the process, and introduce these liquefied gases into the stream of products of conversion passing to the evaporator. These gases may include methane, ethane, unsaturated hydrocarbons and mixtures of the same.

Another distinct method of avoiding the deposition of carbon is to Withdraw a portion of the oil undergoing conversion and reintroduce it into the chamber in such a manner as to scavenge or sweep the surfaces of the chamber upon which carbon is likely to deposit. This may be accomplished by withdrawing the oil through a conduit 3G, connected with the intake side of a suitable pump 3l, and forcing it through a conduit 32 associated with a spraying device positioned within the reaction chamber 6.

It will be appreciated thatI have provided a process wherein a refrigerant or cooling agent may be introduced into the synthetic crude taken from the reaction zone, so as to avoid excessive vaporization of the synthetic crude upon release of pressure and produce a product from the unvaporized material which may be used as a fuel oil.

While I have shown and described the preferred embodiment of my invention, I wish it to be understood that I do not confine myself to the precise details of construction, as it is apparent that many changes and variations may be made therein, by those skilled in the art, without departing from the spirit of the invention, or exceeding the scope of the appended claims.

I claim:

1. A method of converting hydrocarbon oils to obtain hydrocarbons having lower boiling points, comprising heating the oil while passing through a heating element at a rate sufficient to prevent the deposition of carbon on the walls of the element, to a temperature and under a pressure sumcient to bring about'incipient conversion `of the oil, passing the oil under these conditions to an enlarged reaction chamber containing a large body of the oil, and wherein conversion may be consummated, withdrawing products of conversion from the chamber, introducing the products of conversion together with, a liquefied gas refrigerant into an evaporatingl stage, dephlegmating the vapors lresulting frorrthe evaporation, and removing the unevaporated material from the evaporating stage.

2. A method of treating hydrocarbon oils to convert higher boiling hydrocarbons into lower boiling ones, which comprises subjecting the oil in a cracking zone to a cracking temper .ture sulncient to convert higher boiling hydrocabons into lower boiling ones, maintaining the oil in said cracking zone under a pressure suiiicient to maintain it in the so-called liquid phase, Withdrawing the converted products from' said cracking zone and introducing the same into an evaporating zone wherein the vapors and non-Vaporous constituents are separated, and cooling the liquid introduced into the evaporating zone with a liquid which is a gas at normal temperature and pressure.

3. In the treatment of hydrocarbon oils in which the oil is subjected to cracking conditions of temperature and pressure to convert higher boiling hydrocarbons Iinto lower boiling hydrocarbons and the products of conversion are subsequently passed in a regulated stream to an evaporating zone wherein a selected portion of the products are evaporated; the improvement which -comprises introducing a liquid which is a gas at normal temperature and pressure into the stream of converted products being passed to the evaporating zone.

4. In the treatment of hydrocarbon oils in which the oil is subjected to cracking conditions of temperature and pressure to convert higher boiling hydrocarbons into lower boiling ones and the products of conversion are then passed to an evaporating zone, the improvement which comprises introducing a. hydrocarbon liquid which is a. gas at normal temperature and pressure into the conversion-products passed to the evaporating zone.

5. In the process of converting hydrocarbonsA into products suitable for motor fuel, the improvement whichcomprises heating a conned stream of hydrocarbons to quate to eiect conversion ofv hydrocarbons into motor fuel products and thereafter introducing into said stream a cooling medium comprising a liquid which is a gas at normal temperatures 5 and pressures.

WALTER M. CROSS.

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